Alcohols are a class of chemical compounds characterized in that they contain at least one hydroxyl group (OH) and they are extensively used in industry. The best known compound in this class is ethanol or ethyl alcohol. This can be found in alcoholic drinks, cleaning products and pharmaceutical products and it is extensively used as a chemical solvent; it also has an application as a fuel for motor vehicles, which is currently its highest value and most intense use.
The process for producing ethanol is generally carried out on sugar cane, but it may also be carried out on a variety of grains and sources of sugar such as maize, cassava, other roots, sorghum, wheat, barley and molasses, syrup, cane bagasse, potatoes, whey, etc.
The manufacture of ethanol is basically divided into 4 stages: milling, liquefaction, fermentation and distillation. Milling comprises passage from the source of sugar by a processor. In this stage there is obtained a broth which contains a high concentration of water and sugars.
The fermentation part comprises the addition of some kind of yeast which causes the sugar present in the solution to be converted into ethanol. It is the action of enzymes which carries out this work. After this process a fermented must is obtained, and this already contains part of its total volume converted into ethanol.
The must then continues on to the last stage, fractional distillation, and will give rise to a solution having the composition of ethanol and water.
The stage most directly affecting the result of ethanol production, and therefore the most studied, is fermentation, also known as alcoholic fermentation, which is the chemical process of converting sugars, mainly saccharose, glucose and fructose, into ethanol. Microbiological agents which are responsible for the conversion of sugars into ethanol take part in this process.
As it is a widely known process in the state of the art various documents describing processes for the purpose described above can be found. In general the processes concentrate on finding an ideal species or combination of species for the production of ethanol, given that the process used involves a significant loss of the raw materials (sugars), thus reducing the efficiency of the process.
Various documents dealing with different processes for the production of ethanol can be found in the patent literature. American patent U.S. Pat. No. 4,451,566 by Donald B. Spencer describes methods and equipment for the enzyme production of ethanol from fermentable sugars. A sequence of enzymes for catalysing conversion of the sugars into ethanol is maintained in a variety of reaction zones. The fermentable sugar solution passes through these zones in sequence and alcohol is recovered in the last zone. Apart from providing a more efficient reaction than the usual process, this document provides a solution which is onerous, complex and difficult to maintain.
International patent application WO 2007/064545 by Brian Burmaster describes a process for improving the yield of ethanol, reducing the fermentation time and reducing the formation of by-product by monitoring and controlling the oxidation-reduction potential of the fermenter. However this process requires very specific monitoring and is difficult to maintain, causing the process to be expensive, even though it is more efficient.
International patent application WO 2008/024331 by Vladimir Vlad describes a method for magnetic fermentation which includes subjecting a biological material to a static magnetic field in order to affect fermentation of the biological material into a fermented product. The fermentation reaction can take place in alkaline or acid medium and the magnetic field may be positive or negative. This document makes use of a static magnetic field to provide a more propitious environment for the cellular reproduction of microorganisms. Apart from increasing the number of microorganisms in the alcoholic fermentation and thus increasing the reaction yield, this process requires constant monitoring and total control of the reaction, which renders the process expensive.
Noting the limitations of the state of the art the inventor has developed a process for the production of alcohol through the fermentation of sugars which brings benefits such as an increase in the efficiency of the process, through continuous electrical polarisation during the fermentation.